Conventionally, the monitors have been put into practical use, with which 2-parallax images, captured from two viewpoints, are stereoscopically viewable by using a dedicated device, such as stereoscopic glasses. Furthermore, the monitors have been put into practical use in recent years, with which multi-parallax images (e.g., 9-parallax images), captured from multiple viewpoints, are stereoscopically viewable with the naked eye by using a light beam controller, such as a lenticular lens. Here, 2-parallax images or 9-parallax images, displayed on the stereoscopic monitor, are sometimes generated by estimating the depth information on the image that is captured from a single viewpoint and by image processing using the estimated information.
Furthermore, as for medical-image diagnostic apparatus, such as X-ray CT (Computed Tomography) apparatus, MRI (Magnetic Resonance Imaging) apparatus, or ultrasonic diagnostic apparatus, the apparatus that are capable of generating three-dimensional medical image data (hereinafter, volume data) have been put into practical use. Conventionally, the volume data, generated by the medical-image diagnostic apparatus, is two-dimensional images due to various types of image processing, and they are displayed on the general-purpose monitor in two dimensions. For example, the volume data, generated by the medical-image diagnostic apparatus, is two-dimensional images to which three-dimensional information is applied due to a volume rendering operation, and they are displayed on the general-purpose monitor in two dimensions. However, according to the conventional technologies, it is sometimes difficult to display easily observable medical images in a stable manner. Cited references